(1) Field of the Invention
The invention relates to a rotary pump system wherein a rotary pump is driven by a drive means, and, more particularly, is directed to a rotary pump ejection system for firing of projectiles from submarines.
(2) Description of the Prior Art
Submarine rotary pump ejection systems are well known and have been used onboard a large number of submarines of the U.S. Navy. In FIG. 1, there is shown a prior art rotary pump system, which includes a rotary pump 10 having an inlet 12 in communication with a water supply, typically the ocean environment of a submerged submarine. An annularly shaped outlet 14 leads to a holding tank (not shown) from whence the water is admitted to the breech portion of a launch tube, such as a torpedo tube, to force a projectile, such as a torpedo or missile, out of the tube.
Connected to the rotary pump 10, by way of a coupling 16, is a turbine 18 which serves as a drive means for the pump 10. The turbine is driven by air under pressure, which is admitted to the turbine by an air inlet valve 20 which is in communication with a source 22 of high pressure air, typically from the vessel's air head maintained at about 4,500 lbs/in.sup.2.
In operation, the air inlet valve 20, which constitutes a "firing valve" is opened to admit high pressure air to the turbine. Stages of turbine blades in the turbine are caused to rotate a turbine shaft 24 on which the turbine blade stages are mounted. At the downstream end 26 of the turbine 18 there is an air outlet 28 with a muffler 30 disposed therein. A speed sensor 32 is mounted adjacent the turbine shaft 24 and is adapted to determine the speed of the turbine shaft 24, which equals the speed of a rotary pump shaft 34, and communicates such determined speed to a controller 36. The controller 36 is programmed with selected speeds desired of the pump 10 throughout a launch cycle. The controller 36 compares the determined speed received from the speed sensor 32 with the programmed speed at that point in the launch cycle and identifies any difference. The controller 36 then signals the air inlet valve 20 to adjust the admittance of air to the turbine 18 to alter the speed of the turbine, to thereby alter the speed of the pump. The speed monitoring system, including the sensor 32 and the controller 36, operates continuously during a launch to move the projectile through the launch tube at appropriate speeds.
The above-described system, which is designed for modern U.S. submarines, has performed well but has shortcomings which must be addressed. The first is operational, in that there is a built-in lag time between speed detection and speed correction, based upon the fact that it takes time to adjust the firing valve to charge the rate at which air is admitted to the turbine, and time for the turbine speed to adjust to the modified supply of air. A second problem is derived from defense budgetary demands. The firing valve, which is a variable valve adapted to receive and respond to electronic signals from the controller, is a very expensive component of the system.
Thus, there exists a need for a better and less expensive rotary pump speed control system.